answer:Soluble salts – i.e. cations like Ca, Mg, Na. High levels can negatively impact plant growth as plants will not be able to uptake water due to osmosis. Nitrogen – is a major nutrient needed for plant growth. it comes in different forms. nitrate i think is the one that plants can actually uptake, the others not being readily accessible to plants. carbon – can improve microbial activity; i think you judge this by C:N ratio particle size analysis – the distribution of particle sizes in the soil affect drainage, texture… If I were starting a garden, the nutrient levels (both major, i.e. N P K, and minor) and soil classification type would be the first things I’d want to know. If soluble salts were known to be a problem in my area, I would test for that, otherwise, I would be more interested in particle size. Would be interested to know what other people think.